Power semiconductor devices, such as IGBTs or Power MOSFETs, are used in various power electronics applications to switch or rectify electric currents. An important and fast growing application are converter systems for electric or hybrid electric vehicles. In this application, due to the limited available mounting volume, power density is an important requirement for the power electronics converter system. The use of alternative wide-bandgap semiconductor devices, such as silicon carbide (SiC) devices, promises further improvements in this respect.
An approach to reduce self-inductances and mutual inductances of power and signal circuits in a power module may be to route currents in multiple vertically stacked layers.
For example, additional current carrying layers may be placed on top of a substrate. U.S. Pat. No. 8,829,692 B2 shows such layers form on a direct bonded copper substrate.
As proposed in DE 10 2013 015 956 A1, the power semiconductor devices may be completely embedded into a printed circuit board structure and may be directly contacted by copper vias.
Both of these approaches may have disadvantages regarding their manufacturability: The layering of multiple layers one after the other usually require additional bonding processes and the additional interfaces between the multiple layers may pose a risk for the reliability of the power module.
The complete embedding of power semiconductor devices on a printed circuit board, on the other hand, requires special top side metallization, and the process for drilling the vias for top side contacts may be limited regarding the maximum achievable via depths and consequently insulation thicknesses.
US 2014/070394 A1 shows a multi-layer circuit board with cavities, in which semiconductor elements are arranged. However, in US 2014/070394 A1, the heat dissipating substrate is spaced apart from the multi-layer circuit board with a further heat dissipating substrate.
WO 98/44557 A1 shows a multi-layer circuit board with cavities, in which semiconductor elements are arranged. At the bottom of the cavities, the semiconductor elements are attached to a cooling body, which is attached to the multi-layer circuit board.
Additionally, power modules are known from WO 2005/024946 A1, EP 0 597 144 A1, US 2003/076659 A1, US 2014/246681 A1, US 2009/039498 A1 and US 2011/127675 A1.